Ablation of Kcnj10 expression in retinal explants revealed pivotal roles for Kcnj10 in the proliferation and development of Müller glia

PURPOSE: We previously found that Kcnj10, an inwardly-rectifying potassium channel, is a gene expressed in c-kit-positive retinal progenitor cells on P1. The shRNA-mediated screening of the functions of the genes for retinal development in retinal explant culture suggested a role for Kcnj10 in the differentiation of 23Müller glia. In the present study, we extended the work and focused on analyzing the role of Kcnj10 in retinal development. METHODS: shRNA-mediated downregulation of Kcnj10 in retinal explants and the in vivo mouse retina at the P1 stage was performed. Differentiation and proliferation of the retina were examined with immunohistochemistry. The effect of barium (Ba(2+)) treatment, which inhibits potassium currents by blocking potassium channels, on retinal development was examined. RESULTS: When Kcnj10 was downregulated at E18, cellular proliferation and morphological differentiation were perturbed; in particular, a decreased number of Müller glial cells with abnormal morphological maturation was observed. The overexpression of Kcnj10 in retinal progenitors did not result in gross abnormality during retinal development, but rescued the abnormal differentiation induced with sh-Kcnj10. The presence of Ba(2+) in the retinal explant medium led to a phenotype similar to that seen with sh-Kcnj10. Ba(2+) exerts an effect mainly during late retinal development, and sh-Kcnj10 in the P1 retina affected Müller glia maturation, suggesting that Kcnj10 plays a pivotal role in the maturation of retinal cell subsets. A previous study of Kcnj10-knockout mice showed no obvious abnormality in retinal differentiation, especially of Müller glia. We examined the effects of the downregulation of Kcnj10 with in vivo electroporation of sh-Kcnj10 in the P1 retina. Retinal differentiation was perturbed, as seen following the in vitro downregulation of Kcnj10, suggesting that compensatory gene expression and/or signaling occurred in the Kcnj10-knockout mice in the retina, leading to normal eye development. CONCLUSION: Kcnj10 plays a role in Müller glia maturation during retinal development probably through ionic channel activities.